This invention relates to hydrated carbonate-borates of rare-earth elements which are novel compounds and to a method for the manufacture of these borates.
Many carbonates and anhydrous borates of rare-earth elements are already known in the art. Nothing, however, is known in the art about hydrated carbonate-borates of rare-earth elements. The present invention has originated in a discovery made by the inventor while he was continuing a study on the synthesis of various hydrated borates.
Heretofore, hydrated borates have been manufactured by a general procedure comprising the steps of mixing an aqueous solution of borax, boric acid or a mixture thereof with an aqueous solution of a compound which is capable of readily dissolving the component elements making up the borate under preparation, consequently causing eduction of the hydrated borate in the reaction system, subjecting the resultant reaction mixture to filtration and subsequently washing the separated hydrated borate with water or methanol.
Where a hydrated borate is manufactured by this aqueous-solution reaction, however, it is difficult to have substantially all the boron component present in the solution educed in the form of a borate. Generally, the eduction of a borate from its aqueous solution more often than not takes place at a slow rate.
Further, the steps of filtration and washing bring about the possibility of lowering the yield of the hydrated borate because of the ready dissolution of the compound in the course of washing and the possibility of degrading the purity of the produced hydrated borate because of the occasional if not inevitable hydrolysis of the compound under certain conditions.
An object of the present invention is to provide hydrated carbonate-borates of rare-earth elements particularly in the form of pentahydrates, which have never been known in the art.
Another object of the present invention is to provide a method for manufacturing hydrated carbonate-borates of rare-earth elements particularly in the form of pentahydrates, which have never been known in the art, in high yields without inclusion of any residual secondary product by a simple procedure productive of no industrial waste.